AnimationClip

The AnimationClip node enables you to create complex animations based on a timeline. Using AnimationClip nodes, you can animate any node transform field, and also trigger commands that do the following:

• Update text

• Drive interpolators

• Drive imported animations

Platform support

This node is fully supported on XR-Windows, XR-Portable Windows, XR-Portable iOS, XR-Portable Android, and XR-Portable WASM platforms.

Channels and keyframes

The AnimationClip node is based on channels. Each channel represents a field of a node that the AnimationClip is going to manipulate against its timeline. For example, to enable a clip to move a mesh, its position or positionOffset field must be added as a channel.

Keyframes represents specific points on the timeline of a channel in which the channel field must be set to a specific value. Each channel has its own specific set of keyframes.

Curve and impulse channels

You can set up a channel to work into two different ways, by setting its mode field.

• Curve—The values of the channel fields are interpolated between two keyframes. This means that the field value is set in every frame (including the keyframes).

• Impulse—The value of the channel field is set only in the keyframes.

Due to these differences, curve channels can handle movements or states, while the impulse channels are suited to implement calls to commands or coroutines.

Different interpolation curves

When using curve type channels, it’s possible to define the interpolation type between a keyframe and the following keyframe. This is done by setting the keyFrame curve field.

This is the list of currently supported interpolation types.

Supported field types

The Impulse channel can be set to manipulate all the node fields; however, the Curve channel can be set to manipulate node fields of the following types only:

• sint

• sbool

• sfloat

• svec2

• svec3

• svec4

• squat

• smatrix

SMATRIX animations

SMATRIX animations can be performed correctly only on transformation matrices, and they are interpolated as follows.

• Linear interpolation on the translation part

• Spheric interpolation on the matrix quaternion

• Linear interpolation on the scale part

SQUAT fields

SQUAT fields can be animated using Quaternion values or the corresponding Eulerian representation of the quaternion using the following Channel types.

• SQUAT

• SEULER_XYZ

• SEULER_XZY

• SEULER_YXZ

• SEULER_YZX

• SEULER_ZXY

• SEULER_ZYX

Using a Eulerian representation of the Quaternion rotation allows us to make animations of a rotation that spans beyond -180° and +180° more easily. For example, if the users want to animate a bolt unscrewing (rotating around its local Y axis counter-clockwise multiple times) they can more easily animate the bolt’s mesh rotation or rotationOffset fields using a Euler channel.

Using a SQUAT or SMATRIX channel to achieve the same animation would be quite complex, not only because Quaternions are difficult to understand, but also because a keyframe every 180° of rotation would be required. This also means that the same animation created with a SQUAT or SMATRIX channel could never be eased in the same way it can be eased using a Eulerian representation of it, since the latter would require only a starting keyFrame and an ending keyFrame, allowing to ease the overall animation curve as a whole.

For more information on how to create Euler channels for SQUAT fields, see Add Node fields in the Animation Clip Editor section.

Using AnimationClip

The AnimationClip node offers a simple and powerful interface to handle the animation execution.

• start, stop, and pause—These events are used to drive clip execution.

• setCurrentFrameAt—Sets animation to a specific frame when paused or stopped.

• loop—A loop is used to let a clip automatically replay from the beginning when it arrives to the last keyframe.

• rangeStart and rangeEnd—These fields enable you to restrict clip execution within a specific frame range. This can be useful if used together with the loop. Both rangeStart and rangeEnd frames are executed.

Code example

This is a code example for an AnimationClip. Note that the AnimationClip definition is based on nested channels and keyFrames.

<AnimationClip name="proc_animation" fps="60" length="600" loop="true" >

<channel name="mBox001_pos" type="svec3" field="mBox001.position_offset" active="true" mode="curve">

<keyFrame key="0" value="0 0 0" />

<keyFrame key="120" value="0 0.2 0" curve="linear" />

<keyFrame key="240" value="0 0.4 0" curve="linear" />

<keyFrame key="360" value="0 0.2 0" curve="linear"/>

<keyFrame key="480" value="0 0.0 0" curve="linear" />

</channel>

<channel name="blink" type="sstring" field="apm_crt_changeBlink.execute" active="true" mode="impulse">

<keyFrame key="0" value="scene|Box002;scene|Box003" />

<keyFrame key="120" value="scene|Box001" />

<keyFrame key="240" value="scene|Box002" />

<keyFrame key="360" value="scene|Box003" />

<keyFrame key="480" value="scene|Box004" />

</channel>

</AnimationClip>

AnimationClip fields

These are the fields for the AnimationClip node. Only the node-specific fields are indicated, not fields obtained by inheritance.

Field inheritance: NodeBase > AnimationClip

Channel fields

These are the fields supported by the channel. Channel fields can be accessed through the AnimationClip node that the channel is in.

Keyframe fields

These are the fields supported by the keyFrame. KeyFrame fields can be accessed through the AnimationClip node that the keyFrame is grouped in under the corresponding channel.